Volvo Penta D2-40 max alternator size

[Gonaboat]

Hello, My new to me boat has a VP D2-40 and will need an alternator upgrade to cope with charging a lithium bank of 400Ah



My previous boat had a Yanmar 2gmf20 and i had fitted a Balmar 90amp alternator to it. This in the real world was a little big for the engine and it would bring down the RPM significantly when parking in marinas if the batteries were taking full charge.


Ideally i would like to fit a Balmar XT 170amp alternator to the D2-40. Knowing that this style alternator puts out close to its stated amps for an hour or more with Lithium setups has anyone had some real life experience of fitting this size alternator to a D2-40 and and any pitfalls or issues experienced. Its a very common engine so i dont want to try and reinvent the wheel!

[SV_FlyingTigress]

I Have 2x 2016 D2 40-F. One has the original 115A alternator that was changed to externally regulated and the other has the 250A Balmar all connected with a center-fielder unit (which I found so problematic that I have since disabled it). I found that when I purchased the Balmar that that vendor indicated they definitely had a unit that would work with my engine, which I bought. They didn't indicate that, while it would take a change over to serpentine belts (to give traction to drive the additional drag producing the rated amps), that the *pulley* kit was no longer carried for the D2-40* and was not (apparently) otherwise commercially available. I called the gentleman (now deceased I understand, RIP) that made the custom pulley kits for the D2-40 and he indicated that he would need about $3K+ US to make them and that they *should* work. So my solution was to find a narrower J(8?) serpentine pulley that would work, setting the belt tension high and using the electronically configurable clutch function in the Balmar controller to derate the 250A alternator down to producing about 1508Watts/12V .... any higher than that an it would slip...so now it is producing just over 100A when you do the division with charging voltage of over 13V... SO, unless you own a machine shop with a big lathe to make your own pulleys......my advice for your model of engine is 1) consider just externally regulating stock (115A?) alternators or 2) Avoid the huge Balmar alternators unless you first... 3) Solve your pulley conversion before you consider alternators and when you have that dialed, then determine which alternator you can fit. If you want to go around 150A in alternator size, figure out how to get (minimally) a J10 fully set installed and tested, if 200A or more, figure out how to get J12 groove pulleys/bell installed and tested first. I think the D2-40 would drive the 250A (bigger than you need with your stated battery bank) if it had J12 (12 groove) pulleys and a quality belt. If you do solve the pulley situation and they accidentally make a spare set, I can tell you where to send them.. hopefully I just saved you quite a few thousand.

[Gonaboat]

Thanks for the comprehensive real world reply.


It would look like i may be in luck in that the engine seems to have been fitted with a serpentine belt from new but maybe not as wide as needed. I will need to check what size it is when i get down to the boat.


Gordon

[Gonaboat]

As a followup to this thread, does anyone know what standard the foot is on the Volvo Penta Alternator for the d2-40? i cant tell if it is the "hitachi" style or the "J180" without taking it off.


Part number is:A003TR0091ZT

[Tomas From]

Hi, I've done some research regarding this since I'm planning to upgrade my system as well. The original 115 A 12v Mitsubishi alternator in Volvo Penta D2-40 is what I understand it a 4" double foot J-180 mount.

[SV_FlyingTigress]

....ALSO.... if you are using the stock alternators but externally regulated you need to put a LOT of cooling on it so you can charge in the 15000-2200 ish RPM range that would be more normal stilling at anchor or motoring at reduced fuel consumption RPM. If you don't the stock alternator (which isn't build as well as the Ballard for heat tolerance) gets hot and fries because it can produce more amps at those RPM's than it can provide cooling for at those RPMs ......or (if protected by the M618 external regulator temp protection, which you should get) C it will be throttled down to producing an underwhelming amount of current. This is a function of LFP's being able to take prolonged large current inrushes, and probably why palmar makes their alternators to take more heat.

[Trollmann]

Maybe I can help a bit here.
Later D2-40 comes with 5PK-belt and Mitsubishi 115.
Mi115 in common gives no more than about 80A "warm" (under good conditions and at high idle) but usualy even less when "hot"(down to 65A).
The mounting is 4" / J 180 saddle mount (high version, important to get space in the bottom).
XT-250 driven with standard 5PK don´t give a better result than the XT-170, simply because it takes to much torque (not necessarily for the engine, but for the 5PK belt).
My customers here in Europe gets recommended "just" XT-DF4-170-K6, with SP-pulley which is some millimeters longer than the normal K6 from Balmar is.
DF4 together with SP is fitting nearly "perfect" on D2-engines, regarding the foot mount and alignment. If necc., sometimes it is by reason of variations at VP, then the mounting on the -engine- mounting / foot has to get shortend slightly at the back side, but with just about 2 to 4 millimeter (sorry, german, without Inch in the calculator) and so to pluss it with a spacer at the front side again. But that is no big deal to make. After that you just have to modify the original belt-tensioner at the outer end/downside (grind a bit, just to get it over the alternator). So again some spacer too (don´t even think about another angle than exactly 90 degrees to the engine at all), than you are ready to go.

About regulation.
The MC may not be the most easiest thing to program for people who just are able to use there mobil phone and screens. But for the rest of us it is.
Regarding to easy going of the alternator I recommend to reduce the Belt Load Manager to something with 20% (BEL 4), or even lower if your engineroom is to warm. Please remember, the difference temp. between outside and inside alternators (all of them) can easily become about +90°F inside.
To reduce field means to reduce linear. Means it will reduce heating not only at the topp, but at the bottom of the output curve, too. These 80% field left on XT-170 is actually more than enough to get about 80A right over idle, about 110A with just 200 rpm more, and something by 140A while cruising.
And here I talk about "hot".
People who modify the airstream to get better cooling will get surpriced too.
Simple improvements will help a lot.

So, we still talk about simple modifications to get doubled the possible... performance of a Mitsubishi 115. That btw. is a real good alternator too, but here we are talking about how to increase charging and metodes if you need or want more then 65 Amp in the real life. The XT gives it without real problems (if not home made),
and even more to them who care about cooling the airstream.

Thanks for your patience by reading my bad english,
but I hope the almost of you could understand the meanings.